Multi-Layer Golf Balls Comprising Ionomers with a Percent Neutralization Gradient

ABSTRACT

A multilayer golf ball including a core, an optional intermediate layer and a cover, wherein at least one layer includes a first highly neutralized moisture resistant acid polymer composition having a moisture vapor transmission rate of 8 g-mil/100 in 2 /day or less; an adjacent layer includes a second highly neutralized acid polymer; and the two polymer layers form a percent neutralization gradient.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 11/270,066, filed Nov. 9, 2005, which is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/959,751, filed Oct. 6, 2004, which is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/360,233, filed Feb. 6, 2003, now U.S. Pat. No. 6,939,907, which is a continuation-in-part of U.S. patent application Ser. No. 10/118,719, filed Apr. 9, 2002, now U.S. Pat. No. 6,756,436, which claims priority to U.S. Provisional Patent Application Ser. No. 60/301,046, filed Jun. 26, 2001, the entire disclosures of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention is directed to multi-layer golf balls comprising at least two adjacent layers of neutralized polymers, of which at least one layer may be a highly neutralized moisture resistant polymer (HNMRP), whereby the at least two adjacent layers show a percent neutralization gradient that either increases or decreases from the center.

The present invention is also directed to multi-layer golf balls comprising at least two adjacent layers of neutralized polymers, of which at least one layer may be an ionomer, whereby the at least two adjacent layers show a percent neutralization gradient that either increases or decreases from the center.

BACKGROUND OF THE INVENTION

Conventional golf balls can be divided into two general classes: solid and wound. Solid golf balls include one-piece, two-piece (i.e., solid core and a cover), and multi-layer (i.e., solid core of one or more layers and/or a cover of one or more layers) golf balls. Wound golf balls include a solid, hollow, or fluid-filled center, surrounded by a tensioned elastomeric material, and a cover.

Golf ball core and cover layers are typically constructed with polymer compositions including, for example, polybutadiene rubber, polyurethanes, polyamides, ionomers, and blends thereof. Ionomers, particularly highly neutralized ionomers, are a preferred group of polymers for golf ball layers because of their toughness, durability, and wide range of hardness values. However, conventional highly neutralized polymers (RNP) are hydrophilic due to the use of magnesium ions to neutralize the ionomers. Therefore the conventional highly neutralized ionomers can absorb a significant amount of moisture that can lead to processing difficulties and reduction in golf ball performance such as decreased coefficient of restitution (“COR”) and stiffness due to the plasticization of ionic aggregates by water molecules.

Therefore, there remains a need for improved water or moisture resistant golf ball compositions and, in particular, highly neutralized or filly neutralized ionomers. The present invention exemplifies the use of these novel compositions in at least two adjacent layers of neutralized ionomeric polymers with a percent neutralization gradient that either increases or decreases from the center. At least one of the at least two adjacent layers can be a highly neutralized moisture resistant polymer,

SUMMARY OF THE INVENTION

The present invention is directed to a multilayer golf ball including a core, an intermediate layer, and a cover, the intermediate layer and cover bring adjacent to each other. At least one of the intermediate layer or cover includes a first highly neutralized moisture resistant acid polymer composition having a moisture vapor transmission rate of 8 g-mil/100 in2/day or less. The adjacent layer (intermediate layer or cover) not including the first highly neutralized moisture resistant acid polymer includes a second highly neutralized acid polymer. The two adjacent layers, in tandem, form a percent neutralization gradient.

In one embodiment, the percent neutralization gradient progressively increases toward the outside of the golf ball. Alternatively, the percent neutralization gradient progressively decreases toward the outside of the golf ball. The first highly neutralized moisture resistant acid polymer preferably has a moisture vapor transmission rate of 5 g-mil/100 in2/day or less, more preferably 3 g-mil/100 in2/day or less. At least one of the first and second highly neutralized acid polymers comprise acid groups that are at least 90% neutralized, more preferably 100% neutralized. The first highly neutralized moisture resistant acid polymer is neutralized with less hydrophilic cation sources, such as metal ions and compounds of potassium, cesium, calcium, barium, manganese, copper, zinc, and tin.

The total golf ball has a first volume and the two layers formed from the first and second highly neutralized acid polymers combine to have a second volume that is at least 40 percent of the first volume, more preferably at least 70 percent of the first volume, most preferably at least 90 percent of the first volume.

The present invention is also directed to a multi-layer golf ball including a core and at least three adjacent layers comprising highly-neutralized acid polymers. The three adjacent layers include an innermost layer, an intermediate layer, and an outermost layer. The golf ball has a first volume and a combination of the innermost, intermediate, and outermost adjacent layers form a percent neutralization gradient and have a second volume that is at least about 40% of the first volume. More preferably, the second volume is at least 70% of the first volume, most preferably the second volume is at least 90% of the first volume.

In one embodiment, the percent neutralization gradient progressively increases toward the outside of the golf ball. Preferably, the percent neutralization of the innermost layer is from about 20 to 70, the percent neutralization of the intermediate layer is from about 50 to 90, and the percent neutralization of the outermost layer is from about 70 to 100, and wherein the percent neutralization of the innermost layer is less than the percent neutralization of the intermediate layer, and the percent neutralization of the intermediate layer is less than the percent neutralization of the outermost layer.

In an alternative embodiment, the percent neutralization gradient progressively decreases toward the outside of the golf ball. Preferably, the percent neutralization of the innermost layer is from about 70 to 100, the percent neutralization of the intermediate layer is from about 50 to 90, and the percent neutralization of the outermost layer is from about 20 to 70, and wherein the percent neutralization of the innermost layer is greater than the percent neutralization of the intermediate layer, and the percent neutralization of the intermediate layer is greater than the percent neutralization of the outermost layer.

The present invention is further directed to a multi-layer golf ball including a core layer, an intermediate layer adjacent to the core layer, and an outermost layer adjacent to the intermediate layer. The golf ball has a first volume and at least two of the adjacent layers comprise a neutralized acid polymer, said two adjacent layers combining to form a percent neutralization gradient. Preferably, the combined adjacent layers have a second volume that is at least 40% of the first volume, more preferably at least 70% of the first volume, and most preferably at least 90% of the first volume.

In one embodiment, the percent neutralization gradient progressively increases towards the outside of the golf ball. In an alternative embodiment, the percent neutralization gradient progressively decreases towards the outside of the golf ball. The neutralized acid polymer typically includes acid groups that are neutralized from about 80 to 100%.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which form a part of the specification and are to be read in conjunction therewith and in which like reference numerals are used to indicate like parts in the various views:

FIG. 1 is a front view of a golf ball in accordance to the present invention;

FIG. 2 is a cross-sectional view of the golf ball in FIG. 1 showing a solid core, an intermediate layer and a cover; and

FIG. 3 is a cross-sectional view of another golf ball in accordance to the present invention showing a solid core with multiple intermediate layers and a cover.

DETAILED DESCRIPTION OF THE INVENTION

The invention is directed to multilayer golf balls comprising at least two adjacent layers of highly neutralized acid polymers (HNP), of which at least one layer can be a highly neutralized moisture resistant polymer (HNMRP), whereby the at least two adjacent layers form a percent neutralization gradient that either increases or decreases from the center. Preferably, when the golf ball has two HNP layers, one of them is an HNMRP layer.

The invention is also directed to multilayer golf balls comprising at least 40 volume percent thermoplastic materials while having a percent neutralization gradient that either increases or decrease. The core of the golf balls can be thermoplastic or non-thermoplastic materials. Preferably, the thermoplastic material is about at least 90 volume percent.

Golf balls of the invention may include two-piece and multi-layer golf balls having a variety of core materials, intermediate layers, covers, and coatings. As shown generally in FIGS. 1, 2 and 3, where like numbers designate like parts, reference number 10 broadly designates a golf ball in accordance to the present invention. Golf ball 10 preferably has a core 12, an intermediate layer 14 and a cover 16. The intermediate layer 14 may be a single layer as in FIG. 2. The intermediate layer 14 may also comprise multiple layers ranging from 1 to 6, as illustrated by 14 a, 14 b and 14 c in FIG. 3. The intermediate layer may also be an inner cover layer, an outer core layer, or a mantle layer, and the ball may have up to 6 intermediate layers.

As used herein, “highly neutralized acid polymer” (HNP) refers to the acid polymer after at least 70%, preferably at least 80%, more preferably at least 90%, even more preferably at least 95%, and most preferably 100%, of the acid groups thereof are neutralized.

Conventional HNP materials are hydrophilic due to the highly hydrophilic nature of the cation sources traditionally used to neutralize the ionomers, such as magnesium and magnesium salts of fatty acids. As a result, conventional HNP materials may absorb a significant amount of moisture from 2,000 to 10,000 parts per million (ppm), causing problems in the manufacturing process and negatively affecting the performance of the golf balls.

As used herein, “highly neutralized moisture resistant polymers” (HNMRP) are created when less hydrophilic cation source is used to produce HNP's. The resulting HNP's have improved moisture vapor transmission properties. For example, a polymer composition comprising an HNP, wherein the HNP is produced using a less hydrophilic cation source, can have a moisture vapor transmission rate (MVTR) of 8 g-mil/100 in²/day or less, or preferably 5 g-mil/100 in²/day or less, or more preferably 3 g-mil/100 in²/day or less. The MVTR can be less than 1 g-mil/100 in²/day. As used herein, moisture vapor transmission rate (MVTR) is given in g-mil/100 in²/day, and is measured at 20° C., and according to ASTM F1249-99. The HNMRP's can be considered as specialized HNP's that possess moisture resistant properties. Therefore, HNMRP's can be considered as a subset of HNP's.

As used herein, “less hydrophilic” refers to cation sources which are less hydrophilic than conventional magnesium-based cation sources. Using one or more of such less hydrophilic cation sources, the HNMRP's of the present invention are produced. Without being limited to any particular theory, hydrophilicity is related to the strength of hydration of the cations or cation sources. Therefore, HNP that are made with strongly hydrated cations are more hydrophilic, and HNP that are made with weakly hydrated cations are less hydrophilic.

The strength of hydration of cations and anions is useful in predicting the interaction between biopolymers such as proteins and water. For instance, it has been observed that, in the presence of strongly hydrated cations such as magnesium, proteins will precipitate, or salted out, more easily. Known originally as the Hofmeister series, the ranking of the strength of hydration of cations is generally accepted as: Al³⁺>Mg²⁺>Ca²⁺>Li⁺>Na⁺>K⁺>Rb⁺>Cs+>NH₄ ⁺>N(CH₃)₄ ⁺

(Salting Out) (Salting In)

Similarly, the ranking of the strength of hydration of anions is generally accepted as: C₃H₅O(COO)₃ ³⁻>SO₄ ²⁻>PO₄ ²⁻>F⁻>Cl^(−>)Br^(−>)I^(−>)ClO₄ ⁻>SCN⁻

(Salting Out) (Salting In)

See “The Hofmeister Series”, by M. Chaplin, updated 28 Mar. 2006 and available at http://www.1sbu.ac.uk/water/hofmeist.html and references therein. See also “Water 2”, Course Materials for MSE 461, Spring 2006, Cornell U., Instructor D. Grubb and available at http://www.mse.cornell.edu/courses/mse461/Notes/Water_(—)2/water_(—)2.html and references therein.

U.S. Pat. No. 6,013,708 (the '708 patent) to Mallon et al. is an application of the Hofmeister series to the control of solubility of polymers with the use of either “kosmotropic salts” that generally decrease the solubility of substances in water, or “chaotropic salts” that generally increase the solubility of substances in water. Examples of “kosmotropic” anions include sulfate, fluoride, phosphate, acetate, citrate (C₃H₅O(COO)₃ ³⁻), tartrate (—O₂C—CH(OH)—CH(OH)—CO₂ ⁻), and hydrogen phosphate. Examples of “chaotropic” anions include thicyanate, perchlorate, chlorate, bromate, iodide, nitrate and bromide. The disclosure of the '708 patent and references cited therein is incorporated herein by reference.

Examples of suitable less hydrophilic cation sources to make HNMRP's include, but are not limited to, silicone, silane, and silicate derivatives and complex ligands; metal ions and compounds of rare earth elements; and less hydrophilic metal ions and compounds of alkali metals, alkaline earth metals, and transition metals; and combinations thereof. Particular less hydrophilic cation sources include, but are not limited to, metal ions and compounds of potassium, cesium, calcium, barium, manganese, copper, zinc, tin, and rare earth metals. Potassium-based compounds are a preferred less hydrophilic cation source, and particularly Oxone®, commercially available from E. I. DuPont de Nemours and Company. Oxone® is a monopersulfate compound wherein potassium monopersulfate is the active ingredient present as a component of a triple salt of the formula 2KHSO₅.KHSO₄.K₂SO₄ [potassium hydrogen peroxymonosulfate sulfate (5:3:2:2)]. The amount of less hydrophilic cation source used is readily determined based on the desired level of neutralization.

As used herein, “percent neutralization gradient” is a description of the extents of neutralization of adjacent layers of ionomers. The percent neutralization gradient of the golf balls of the invention either increases or decrease from the center.

In one embodiment having two adjacent layers of HNP, golf balls with an increasing percent neutralization gradient may be constructed when the neutralization of the inner layer is 70% or less while the neutralization of the outer layer can be from about 71 to 100%. An increasing percent neutralization gradient may also be achieved when the neutralization of the inner layer is greater than about 70% to about 95% while the neutralization of the outer layer is about 100%. Conversely, golf balls with a decreasing percent neutralization gradient may be built when the neutralization of the inner layer is from about 75% to about 100% while the neutralization of the outer layer is about 70%.

In the embodiment having two adjacent layers of ionomers, the adjacent layers may comprise core 12 and intermediate layer 14, or intermediate layer 14 and cover 16, as depicted in FIG. 2. The adjacent layers of HNP may also comprise the multiple intermediate layers such as 14 a and 14 b, or 14 b and 14 c as depicted in FIG. 3. Preferably, at least one of the two adjacent layers of ionomer in this embodiment comprises an HNP, optionally where the HNP is an HNMRP. Alternatively, both adjacent layers of Ionomer are HNP, one or both of which may be an HNMRP.

In a different embodiment having three or more adjacent layers of ionomer, golf balls with an increasing percent neutralization gradient may be assembled wherein the percent neutralization of the innermost layer is from about 20 to 70, while the percent neutralization of the second or intermediate adjacent layer is greater than the percent neutralization of the innermost layer and is about 50 to 90% neutralized. The third or outermost adjacent layer has a percent neutralization greater than that of the intermediate layer and is about 70 to 100% neutralized. Conversely, golf balls with a decreasing percent neutralization gradient may be assembled wherein the percent neutralization of the innermost layer is about 70 to 100 while the percent neutralization of the second or intermediate adjacent layer is smaller than the percent neutralization of the innermost layer and is about 50 to 90% neutralized. The third or outermost adjacent layer has a percent neutralization smaller than that of the intermediate layer and is about 20 to 70% neutralized.

In the embodiment having three or more adjacent layers of ionomer, the adjacent layers may comprise the core 12 and the multiple intermediate layers 14 a and 14 b as depicted in FIG. 3. The adjacent layers may also comprise three multiple intermediate layers such as 14 a, 14 b and 14 c in FIG. 3. Preferably, at least one of the three or more adjacent layers of ionomer comprises HNP and preferably an HNMRP. Cover layer 16 may also comprise HNP and follow the percent neutralized gradient of the inner layers.

From a different perspective, the volume percentage of the thermoplastic materials in the multilayer golf balls of the invention can be at least 40%, preferably at least 70%, and most preferably at least 90%, while the percent neutralization gradient of adjacent layers of HNP increases or decreases from the center of the ball.

The core of the multilayer golf balls having at least 40 volume percent of thermoplastic materials is preferably solid, but may be hollow or liquid-, gel-, or gas-filled. Core 12 can be made from any suitable core materials, including neutralized thermoplastics such as ionomer resins, polyamides, and polyesters. See commonly-owned U.S. Pat. No. 6,999,638 (the '638 patent) to Rajagopalan and Sullivan and references cited therein for additional examples of thermoplastic materials. The core 12 can also be made from non-thermoplastics or thermosetting polymers such as natural rubber, polybutadiene (PBD), polyisoprene, and styrene-butadiene. See also the '638 patent and referenced cited therein for additional examples of non-thermoplastic materials.

As shown in Table 1, if the size of the non-thermoplastic core is about 1.420 inches in diameter, the volume percentage of the thermoplastic materials will be about 39.6% for a conventional golf ball with a diameter of 1.68 inches. If the size of the non-thermoplastic core decreases to 1.400, 1.250 and 1.00 inches in diameter, the volume percentage of the thermoplastic materials such as HNP will increase to 42.1, 58.8 and 78.9, respectively. TABLE 1 Size of Non-Thermoplastic Materials Relative to Volume Percentage of Neutralized Thermoplastic Materials. Size of Inner Non- Thermoplastic Volume % of Inner Non- Volume % of Neutralized Materials (Inches) Thermoplastic Materials Thermoplastic Materials 1.420 60.4 39.6 1.400 57.9 42.1 1.250 41.2 58.8 1.000 21.1 78.9

The cover 16 of the golf balls of the invention may contain one or more layers, such as a double cover having an inner and outer cover layer. Preferably, the cover 16 is one layer.

The golf balls of the invention demonstrate desirable qualities such as distance, spin, speed and playability by having increasing or decreasing percent neutralization gradient between at least two adjacent ionomeric layers. By incorporating additional features such as HNMRP, volume percentage of thermoplastic materials and the size of the core, separately or in combination, the golf balls of the invention achieve additional advantages.

The Ionomers of the present invention are salts of homopolymers and copolymers of α,β-ethylenically unsaturated mono- or dicarboxylic acids, and combinations thereof. The term “copolymer,” as used herein, includes polymers having two types of monomers, those having three types of monomers, and those having more than three types of monomers. Preferred acids are (meth) acrylic acid, ethacrylic acid, maleic acid, crotonic acid, fuimaric acid, itaconic acid. (Meth) acrylic acid is particularly preferred. As used herein, “(meth) acrylic acid” means methacrylic acid and/or acrylic acid. Likewise, “(meth) acrylate” means methacrylate and/or acrylate. Preferred acid polymers are copolymers of a C₃ to C₈ α,β-ethylenically unsaturated mono- or dicarboxylic acid and ethylene or a C₃ to C₆ α-olefin, optionally including a softening monomer. Particularly preferred acid polymers are copolymers of ethylene and (meth) acrylic acid.

When a softening monomer is included, the acid polymer is referred to herein as an E/X/Y-type copolymer, wherein E is ethylene, X is a C₃ to C₈ α,β-ethylenically unsaturated mono- or dicarboxylic acid, and Y is a softening monomer. The softening monomer is typically an alkyl (meth) acrylate, wherein the alkyl groups have from 1 to 8 carbon atoms. Preferred E/X/Y-type copolymers are those wherein X is (meth) acrylic acid and/or Y is selected from (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, methyl (meth) acrylate, and ethyl (meth) acrylate. More preferred E/X/Y-type copolymers are ethylene/(meth) acrylic acid/n-butyl acrylate, ethylene/(meth) acrylic acid/methyl acrylate, and ethylenc/(meth) acrylic acid/ethyl acrylate.

The amount of ethylene or C₃ to C₆ α-olefin in the acid copolymer is typically at least 15 wt %, preferably at least 25 wt %, more preferably least 40 wt %, and even more preferably at least 60 wt %, based on the total weight of the copolymer. The amount of C₃ to C₈ α,β-ethylenically unsaturated mono- or dicarboxylic acid in the acid copolymer is typically from 1 wt % to 35 wt %, preferably from 4 wt % to 35 wt %, more preferably from 6 wt % to 35 wt %, and even more preferably from 8 wt % to 20 wt %, based on the total weight of the copolymer. The amount of optional softening comonomer in the acid copolymer is typically from 0 wt % to 50 wt %.

Suitable acid polymers also include partially neutralized acid polymers. Examples of suitable partially neutralized acid polymers include, but are not limited to, Surlyn® ionomers, commercially available from E. I. DuPont de Nemours and Company; AClyn® ionomers, commercially available from Honeywell International Inc.; and Iotek® ionomers, commercially available from Exxon Mobil Chemical Company. Additional suitable acid polymers are more fully described, for example, in U.S. Pat. No. 6,953,820 and U.S. Patent Application Publication No. 2005/0049367, the entire disclosures of which are hereby incorporated herein by reference.

The acid polymers of the present invention can be direct copolymers wherein the polymer is polymerized by adding all monomers simultaneously, as described in, for example, U.S. Pat. No. 4,351,931, the entire disclosure of which is hereby incorporated herein by reference. Ionomers can be made from direct copolymers, as described in, for example, U.S. Pat. No. 3,264,272 to Rees, the entire disclosure of which is hereby incorporated herein by reference. Alternatively, the acid polymers of the present invention can be graft copolymers wherein a monomer is grafted onto an existing polymer, as described in, for example, U.S. Patent Application Publication No. 2002/0013413, the entire disclosure of which is hereby incorporated herein by reference.

Compositions of the present invention may include at least one inventive HNMRP (i.e., produced using a less hydrophilic cation source), and optionally include one or more additional HNP(s). When included, the additional HNP's can be one or more inventive HNP's (i.e., produced with one or more cations described above) and/or one or more conventional HNP(s) (i.e., produced using a conventional cation source). The total amount of HNP(s) in the composition is preferably at least 30 wt %, more preferably at least 50 wt %, even more preferably from 50 wt % to 99.5 wt %, and even more preferably from 60 wt % to 98 wt %, based on the total polymeric weight of the composition. Preferably, the amount of inventive HNP(s) present in the composition is at least 30 wt %.

In order to be processable, the ionomer-containing composition of the present invention has a melt flow index of at least 0.5 g/10 min. Preferably, the melt flow index of the ionomer-containing composition is from 0.5 g/10 min to 100.0 g/10 min, more preferably from 1.0 g/10 min to 10.0 g/10 min, and even more preferably from 1.0 g/10 min to 5.0 g/10 min.

Compositions of the present invention may optionally contain one or more melt flow modifier(s). Suitable melt flow modifiers include organic acids and salts thereof, polyamides, polyesters, polyacrylates, polyurethanes, polyethers, thermoplastic polyureas, polyhydric alcohols, and combinations thereof. Suitable organic acids are aliphatic organic acids, aromatic organic acids, saturated mono-functional organic acids, unsaturated monofunctional organic acids, multi-unsaturated mono-functional organic acids, and dimerized derivatives thereof Particular examples of suitable organic acids include, but are not limited to, caproic acid, caprylic acid, capric acid, lauric acid, stearic acid, behenic acid, erucic acid, oleic acid, linoleic acid, myristic acid, benzoic acid, palmitic acid, phenylacetic acid, naphthalenoic acid, dimerized derivatives thereof. When one or more organic acid salt(s) are included in compositions of the present invention, the cation source used to produce the organic acid salt(s) is preferably a less hydrophilic cation source. Suitable organic acids are more fully described, for example, in U.S. Pat. No. 6,756,436, the entire disclosure of which is hereby incorporated herein by reference.

Additional non-fatty acid melt flow modifiers, suitable for use in compositions of the present invention, include those described in co pending U.S. patent application Ser. Nos. 11/216,725 and 11/216,726, the entire disclosures of which are hereby incorporated herein by reference.

Compositions of the present invention may optionally contain one or more additives in an amount of from 0 wt % to 60 wt %, based on the total weight of the composition. Suitable additives include, but are not limited to, chemical blowing and foaming agents, optical brighteners, coloring agents, fluorescent agents, whitening agents, NV absorbers, light stabilizers, defoaming agents, processing aids, mica, talc, nano-fillers, antioxidants, stabilizers, softening agents, fragrance components, plasticizers, impact modifiers, TiO₂, acid copolymer wax, surfactants, and fillers, such as zinc oxide, tin oxide, barium sulfate, zinc sulfate, calcium oxide, calcium carbonate, zinc carbonate, barium carbonate, clay, tungsten, tungsten carbide, silica, lead silicate, regrind (recycled material), and mixtures thereof. Suitable additives are more fully described in, for example, U.S. Patent Application Publication No. 2003/0225197, the entire disclosure of which is hereby incorporated herein by reference.

Compositions may optionally be produced by blending the ionomer of the present invention with one or more additional polymers, such as thermoplastic polymers and elastomers. Examples of thermoplastic polymers suitable for blending with the invention HNPs include, but are not limited to, polyolefins, polyamides, polyesters, polyethers, polycarbonates, polysulfones, polyacetals, polylactones, acrylonitrile-butadiene-styrene resins, polyphenylene oxide, polyphenylene sulfide, styrene-acrylonitrile resins, styrene maleic anhydride, polyimides, aromatic polyketones, ionomers and ionomeric precursors, acid copolymers, conventional HNPs, polyurethanes, grafted and non-grafted metallocene-catalyzed polymers, single-site catalyst polymerized polymers, high crystalline acid polymers, cationic ionomers, and combinations thereof. Particular polyolefins suitable for blending include one or more, linear, branched, or cyclic, C₂-C₄₀ olefins, particularly polymers comprising ethylene or propylene copolymerized with one or more C₂-C₄₀ olefins, C₃-C₂₀ α-olefins, or C₃-C₁₀ α-olefins. Particular conventional HNPs suitable for blending include, but are not limited to, one or more of the HNPs disclosed in U.S. Pat. Nos. 6,756,436, 6,894,098, and 6,953,820, the entire disclosures of which are hereby incorporated herein by reference. Examples of elastomers suitable for blending with the invention polymers include all natural and synthetic rubbers, including, but not limited to, ethylene propylene rubber (“EPR”), ethylene propylene diene rubber (“EPDM”), styrenic block copolymer rubbers (such as SI, SIS, SB, SBS, SIBS, and the like, where “S” is styrene, “I” is isobutylene, and “B” is butadiene), butyl rubber, halobutyl rubber, copolymers of isobutylene and p-alkylstyrene, halogenated copolymers of isobutylene and p-alkylstyrene, natural rubber, polyisoprene, copolymers of butadiene with acrylonitrile, polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber, acrylonitrile chlorinated isoprene rubber, and polybutadiene rubber (cis and trans). Additional suitable blend polymers include those described in U.S. Pat. No. 5,981,658, for example at column 14, lines 30 to 56, the entire disclosure of which is hereby incorporated herein by reference. The blends described herein may be produced by post-reactor blending, by connecting reactors in series to make reactor blends, or by using more than one catalyst in the same reactor to produce multiple species of polymer. The polymers may be mixed prior to being put into an extruder, or they may be mixed in an extruder.

Compositions of the present invention typically have a flexural modulus of from 3,000 psi to 200,000 psi, preferably from 5,000 psi to 150,000 psi, more preferably from 10,000 psi to 125,000 psi, and even more preferably from 10,000 psi to 100,000 psi. The material hardness of the composition is generally from 30 Shore D to 80 Shore D. In embodiments wherein the composition is present in a golf ball center, the composition preferably has a material hardness of from 30 Shore D to 50 Shore D. In embodiments wherein the composition is present in a golf ball cover layer, an outer core layer, or an intermediate layer disposed between the core and the cover, the composition preferably has a material hardness of from 30 Shore D to 70 Shore D. The notched izod impact strength of the compositions of the present invention is generally at least 2 ft·lb/in, as measured at 23° C. according to ASTM D256.

The present invention is not limited by any particular method or any particular equipment for making the composition. In a preferred embodiment, the composition is prepared by the following process. An acid polymer, preferably ethylene/(meth) acrylic acid, is fed into a melt extruder, such as a single or twin screw extruder. A suitable amount of a less hydrophilic cation source is added to the molten acid polymer. The acid polymer may be partially neutralized prior to contact with the cation source, preferably with a cation source selected from metal ions and compounds of calcium, magnesium, and zinc. The acid polymer/cation mixture is intensively mixed prior to being extruded as a strand from the die-head. Optionally, a less hydrophilic cation source based on a fatty acid salt or other non-fatty acid salt melt flow modifier is incorporated during the HNP production. In a particular aspect of this embodiment, the ethylene/(meth) acrylic acid copolymer is selected from Nucrel® acid copolymers, commercially available from E. I. DuPont de Nemours and Company (such as Nucrel® 960, an ethylene/methacrylic acid copolymer) and Primacor® polymers, commercially available from Dow Chemical Company (such as Primacor® XUS 60758.0L and XUS60751.18, ethylene/acrylic acid copolymers containing 13.5% and 15.0% acid, respectively).

Compositions of the present invention can be used in a variety of applications. For example, HNP-containing compositions are suitable for use in golf equipment, including, but not limited to, golf balls, golf shoes, and golf clubs.

The present invention is not limited by any particular process for forming the golf ball layer(s). It should be understood that the layer(s) can be formed by any suitable technique, including injection molding, compression molding, casting, and reaction injection molding.

In a preferred embodiment, the present invention provides a multi-layer golf ball having a compression molded rubber core, at least two adjacent injection or compression molded HNP intermediate layers, one of which comprises an HNMRP that is produced using a less hydrophilic cation source, and a polyurethane or polyurea outer cover layer. The polyurethane or polyurea outer cover layer material can be thermoset or thennoplastic. Thermoset materials can be formed into golf ball layers by conventional casting or reaction injection molding techniques. Thermoplastic materials can be formed into golf ball layers by conventional compression or injection molding techniques. Light stable polyureas and polyurethanes are preferred for the outer cover layer material. Preferably, the rubber core composition comprises a rubber, a crosslinking agent, a filler, a co-crosslinking agent or free radical initiator, and optionally a cis-to-trans catalyst. Typical rubber materials include natural and synthetic rubbers, including, but not limited to, polybutadiene and styrene-butadiene. The crosslinking agent typically includes a metal salt, such as a zinc salt or magnesium salt, of an acid having from 3 to 8 carbon atoms, such as (meth) acrylic acid. The free radical initiator can be any known polymerization initiator which decomposes during the cure cycle, including, but not limited to, dicumyl peroxide, 1,1-di-(t-butylperoxy) 3,3,S-trimethyl cyclohexane, a-a bis-(t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5 di-(t-butylperoxy) hexane or di-t-butyl peroxide, and mixtures thereof. Suitable types and amounts of rubber, crosslinking agent, filler, co-crosslinking agent, and initiator are more fully described in, for example, U.S. Patent Application Publication No. 2003/0144087, the entire disclosure of which is hereby incorporated herein by reference. Reference is also made to U.S. Patent Application Publication No. 2003/0144087 for various ball constructions and materials that can be used in golf ball core, intermediate, and cover layers.

In another preferred embodiment, the present invention provides a multi-layer golf ball having a solid core, an outer core layer, an inner cover layer and a cover, wherein the outer core layer is formed from a composition comprising an HNMRP that is produced using a less hydrophilic cation source, and the inner cover layer comprises an HNP. In a particular aspect of this embodiment, the composition has a moisture vapor transmission rate of less than 8 g-mil/100 in²/day, thereby reducing the penetration of moisture into the core. In another particular aspect of this embodiment, the HNP is preferably based on an ethylene/(meth) acrylic acid copolymer, which may, but preferably does not, contain a softening comonomer. The solid core may be formed from any suitable core material, and is preferably formed from a conventional rubber selected from polybutadiene, polyisoprene, ethylene propylene rubber (“EPW”), ethylene propylene diene rubber (“EPDM”), styrenic block copolymer rubbers (such as SI, SIS, SB, SBS, SIBS, and the like, where “S” is styrene, “I” is isobutylene, and “BB” is butadiene), butyl rubber, halobutyl rubber, copolymers of isobutylene and p-alkylstyrene, halogenated copolymers of isobutylene and p-alkylstyrene, natural rubber, copolymers of butadiene with acrylonitrile, polychloroprene, alkyl acrylate rubber, chlorinated isoprene rubber, and acrylonitrile chlorinated isoprene rubber. The diameter of the core is preferably from 1.40 inches to 1.55 inches. The cover is preferably a tough, cut-resistant material, selected from conventional golf ball cover materials based on the desired performance characteristics. The cover may comprise one or more layers, and preferably has an overall thickness of from 0.020 inches to 0.045 inches. Suitable cover materials include ionomer resins, blends of ionomer resins, thermoplastic and thermoset urethane, thermoplastic and thermoset urea, (meth)acrylic acid, thermoplastic rubber polymers, polyethylene, and synthetic or natural vulcanized rubber, such as balata. Additional suitable core and cover materials are disclosed, for example, in U.S. Patent Application Publication No. 2005/0164810, U.S. Pat. No. 5,919,100, and PCT Publications WO00/23519 and WO00/29129, the entire disclosures of which are hereby incorporated herein by reference.

In another preferred embodiment, the present invention provides a two-piece or multi-layer golf ball having a center formed from a composition comprising an HNP produced using a less hydrophilic cation source. The HNP is preferably based on an E/X/Y-type polymer. Preferably, the core has a material hardness of from 30 Shore D to 50 Shore D. The cover is preferably a tough, cut-resistant HNPP material. The cover may comprise one or more layers, and preferably has an overall thickness of from 0.020 inches to 0.045 inches.

Golf balls of the present invention generally have a coefficient of restitution (“COR”) of at least 0.800, more preferably at least 0.805, and even more preferably at least 0.810, and an Atti compression of from 75 to 110, preferably from 90 to 95. As used herein, COR is defined as the ratio of the rebound velocity to the inbound velocity when balls are fired into a rigid plate. In determining COR, the inbound velocity is understood to be 125 ft/s.

EXAMPLES Example 1 A Two-Piece Golf Ball with Increasing Percent Neutralization Gradient

The inner core of the golf ball is made of HNMRP having a neutralization of about 85% with an Atti compression of about 80. The inner core is covered by an HNP cover having a neutralization of about 100%. The resulting golf ball has an Atti compression less than about 90 and a coefficient of restitution (COR) greater than 0.800.

Example 2

A Two-Piece Golf Ball with Decreasing Percent Neutralization Gradient

The inner core of the golf ball is made of HNMRP having a neutralization of about 100% with an Atti compression of about 80. The inner core is covered by an HNP cover having a neutralization of about 80%. The resulting golf ball has an Atti compression less than about 90 and a coefficient of restitution (COR) greater than 0.800.

Example 3

A Three-Piece Golf Ball with Increasing Percent Neutralization Gradient The inner core of the golf ball is made of polybutadiene of less than 1.4″ diameter. The second layer is made of an HNP layer having a neutralization of about 85% with a Shore D of greater than about 60. The outermost layer comprises UNMRP having neutralization of about 100%. The resulting golf ball has an Atti compression less than about 95 and a coefficient of restitution (COR) greater than 0.800.

Example 4

A Three-Piece Golf Ball with Decreasing Percent Neutralization Gradient

The inner core of the golf ball is constructed of HNMRP having a neutralization of about 100% and an Atti compression of about 80. The second layer is made of HNP having a neutralization of about 85% and a Shore D of greater than about 60. The outermost layer is made of a thermoplastic material having a neutralization of less than about 80%. The resulting golf ball has an Atti compression less than about 95 and a coefficient of restitution (COR) greater than 0.800.

In accordance with other embodiments, the core of the inventive multi-layer golf ball may have a thermoset layer and two or more neutralized ionomeric layers having a percent neutralization gradient. Preferably, the multi-layer ball contains more than about 40% neutralized ionomers. In one embodiment, the thermoset layer can be the centermost core.

The core of the multi-layer golf ball may comprise thermosetting materials such as the reaction product that includes a cis-to-trans catalyst, a resilient polymer component having polybutadiene, a free radical source, and optionally, a crosslinking agent, a filler, or both.

Preferably, the polybutadiene reaction product is used to form at least a portion of the core of the golf ball, and further discussion below relates to this embodiment for preparing the core.

Preferably, the reaction product has a first dynamic stiffness measured at −50° C. that is less than about 130 percent of a second dynamic stiffness measured at 0° C. More preferably, the first dynamic stiffness is less than about 125 percent of the second dynamic stiffness. Most preferably, the first dynamic stiffness is less than about 110 percent of the second dynamic stiffness.

The cis-to-trans conversion requires the presence of a cis-to-trans catalyst, such as an organosulfur or metal-containing organosulfur compound, a substituted or unsubstituted aromatic organic compound that does not contain sulfur or metal, an inorganic sulfide compound, an aromatic organometallic compound, or mixtures thereof. The cis-to-trans catalyst component may include one or more of the cis-to-trans catalysts described herein. For example, the cis-to-trans catalyst may be a blend of an organosulfur component and an inorganic sulfide component.

The preferred organosulfur components include 4,4′-diphenyl disulfide, 4,4′-ditolyl disulfide, or 2,2′-benzamido diphenyl disulfide, or a mixture thereof An additional preferred organosulfur components include, but are not limited to, pentachlorothiophenol, zinc pentachlorothiophenol, non-metal salts of pentachlorothiophenol such as ammonium salt of pentachlorothiophenol magnesium pentachlorothiophenol, cobalt pentachlorothiophenol, pentafluorothiophenol, zinc pentafluorothiophenol, and blends thereof. Preferred candidates are pentachlorothiophenol (available from Strucktol Company of Stow, Ohio), zinc pentachlorothiophenol (available from eChinachem of San Francisco, Calif.), and blends thereof. Additional examples are described in commonly-owned copending U.S. patent application Ser. No. 10/882,130, which is incorporated herein by reference in its entirety.

The organosulfur cis-to-trans catalyst, when present, is preferably present in an amount sufficient to produce the reaction product so as to contain at least about 12 percent trans-polybutadiene isomer, but typically is greater than about 32 percent trans-polybutadiene isomer based on the total resilient polymer component. In another embodiment, metal-containing organosulfur components can be used according to the invention. Suitable metal-containing organosulfur components include, but are not limited to, cadmium, copper, lead, and tellurium analogs of diethyldithiocarbamate, diamyldithiocarbamate, and dimethyldithiocarbamate, or mixtures thereof. Additional suitable examples of can be found in commonly owned and co-pending U.S. patent application Ser. No. 10/402,592.

Suitable substituted or unsubstituted aromatic organic components that do not include sulfur or a metal include, but are not limited to, 4,4′-diphenyl acetylene, azobenzene, or a mixture thereof. The aromatic organic group preferably ranges in size from C₆ to C₂₀, and more preferably from C₆ to C₁₀. Suitable inorganic sulfide components include, but are not limited to titanium sulfide, manganese sulfide, and sulfide analogs of iron, calcium, cobalt, molybdenum, tungsten, copper, selenium, yttrium, zinc, tin, and bismuth.

The cis-to-trans catalyst can also include a Group VIA component. Elemental sulfur and polymeric sulfur are commercially available from, e.g., Elastochem, Inc. of Chardon, Ohio. Exemplary sulfur catalyst compounds include PB(RM-S)-80 elemental sulfur and PB(CRST)-65 polymeric sulfur, each of which is available from Elastochem, Inc. An exemplary tellurium catalyst under the trade name TELLOY and an exemplary selenium catalyst under the tradename VANDEX are each commercially available from RT Vanderbilt.

A free-radical source, often alternatively referred to as a free-radical initiator, is required in the composition and method. The free-radical source is typically a peroxide, and preferably an organic peroxide. Suitable free-radical sources include di-t-amyl peroxide, di(2-t-butyl-peroxyisopropyl)benzene peroxide, 3,3,5-trimethyl cyclohexane, a-a bis(t-butylperoxy) diisopropylbenzene, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, dicumyl peroxide, di-t-butyl peroxide, 2,5-di-(t-butylperoxy)-2,5-dimethyl hexane, n-butyl-4,4-bis(t-butylperoxy)valerate, lauryl peroxide, benzoyl peroxide, t-butyl hydroperoxide, and the like, and any mixture thereof.

A crosslinking agent is included to increase the hardness of the reaction product. Suitable crosslinking agents include one or more metallic salts of unsaturated fatty acids or monocarboxylic acids, such as zinc, aluminum, sodium, lithium, nickel, calcium, or magnesium acrylate salts, and the like, and mixtures thereof Preferred acrylates include zinc acrylate, zinc diacrylate (ZDA), zinc methacrylate, and zinc dimethacrylate (ZDMA), and mixtures thereof The crosslinking agent must be present in an amount sufficient to crosslink a portion of the chains of polymers in the resilient polymer component. For example, the desired compression may be obtained by adjusting the amount of crosslinking. This may be achieved, for example, by altering the type and amount of crosslinking agent, a method well-known to those of ordinary skill in the art.

The core composition of the present invention, which may also be used in other layers, may also include fillers, added to the polybutadiene material to adjust the density and/or specific gravity of the core or to the cover. Fillers are typically polymeric or mineral particles. Exemplary fillers include precipitated hydrated silica, clay, talc, asbestos, glass fibers, aramid fibers, mica, calcium metasilicate, barium sulfate, zinc sulfide, lithopone, silicates, silicon carbide, diatomaceous earth, polyvinyl chloride, carbonates such as calcium carbonate and magnesium carbonate, metals such as titanium, tungsten, aluminum, bismuth, nickel, molybdenum, iron, lead, copper, boron, cobalt, beryllium, zinc, and tin, metal alloys such as steel, brass, bronze, boron carbide whiskers, and tungsten carbide whiskers, metal oxides such as zinc oxide, iron oxide, aluminum oxide, titanium oxide, magnesium oxide, and zirconium oxide, particulate carbonaceous materials such as graphite, carbon black, cotton flock, natural bitumen, cellulose flock, and leather fiber, micro balloons such as glass and ceramic, fly ash, and combinations thereof.

Antioxidants may also optionally be included in the polybutadiene material in the centers produced according to the present invention. Antioxidants are compounds that can inhibit or prevent the oxidative degradation of the polybutadiene. Antioxidants useful in the present invention include, but are not limited to, dihydroquinoline antioxidants, amine type antioxidants, and phenolic type antioxidants.

Other optional ingredients, such as accelerators, e.g., tetramethylthiuram, peptizers, processing aids, processing oils, plasticizers, dyes and pigments, as well as other additives well known to those of ordinary skill in the art may also be used in the present invention in amounts sufficient to achieve the purpose for which they are typically used.

An example of the polybutadiene-based material is as follows: 100 parts polybutadiene polymer, 5-10 parts metal acrylate or methacrylate cross-linking agent, 5 parts zinc oxide as the density modifying material, 2 parts dicumyl peroxide as the free radical source, and X part(s) metal powder filler, such as tungsten or other heavy metals, where X depends on the desired specific gravity of the batch and where X is a number, integers and real numbers.

Additionally, neutralized ionomers are also suitable as the core or as one of the intermediate layers for the multi-layer golf balls of this invention. Suitable ionomeric polymers (i.e., copolymer- or terpolymer-type ionomers) include α-olefin/unsaturate-d-carboxylic acid copolymer-type ionomeric or terpolymer-type ionomeric resins. Copolymeric ionomers are obtained by neutralizing at least a portion of the carboxylic groups in a copolymer of an α-olefin and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, with a metal ion. Examples of suitable α-olefins include ethylene, propylene, 1-butene, and 1-hexene. Examples of suitable unsaturated carboxylic acids include acrylic, methacrylic, ethacrylic, α-chloroacrylic, crotonic, maleic, fumaric, and itaconic acid. Copolymeric ionomers include ionomers having varied acid contents and degrees of acid neutralization, neutralized by monovalent or bivalent cations discussed above.

Terpolymeric ionomers are obtained by neutralizing at least a portion of carboxylic groups in a terpolymer of an α-olefin, and an α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, and an α,β-unsaturated carboxylate having 2 to 22 carbon atoms with metal ion. Examples of suitable α-olefins include ethylene, propylene, 1-butene, and 1-hexene. Examples of suitable unsaturated carboxylic acids include acrylic, methacrylic, ethacrylic, α-chloroacrylic, crotonic, maleic, fumaric, and itaconic acid. Terpolymeric ionomers include ionomers having varied acid contents and degrees of acid neutralization, neutralized by monovalent or bivalent cations as discussed above. Examples of suitable ionomeric resins include those marketed under the name SURLYN® manufactured by E.I. DuPont de Nemours & Company of Wilmington, DE, and IOTEK® manufactured by Exxon Mobil Corporation of Irving, Tex.

The ionomers of the core of the invention may also be partially neutralized with metal cations. The acid moiety in the acid copolymer is neutralized about 1 to about 100%, preferably at least about 40 to about 100%, and more preferably at least about 90 to about 100%, to form an ionomer by a cation such as lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc, aluminum, or a mixture thereof

Additionally, DuPont™ Surlyn® ionomers are preferred materials for the cover of the multi-layer golf balls of the invention. These ionomers are ethylene copolymers having acid groups partially neutralized with magnesium, lithium, sodium and zinc ions. TABLE 2 Examples of Ionomers Suitable for Cover Types of Ionomer Wt % Acid Mol % Neutralization A 19.0 38.8 B 9.0 49.6 C 15.0 55.2 D 15.0 47.2 E 15.0 42.2 F 10.0 48.7 G 19.0 37.3 H 19.0 45.3 I 9.0 52.0 J 10.0 55.0 K 11.0 35.7 L 15.0 56.2 M 15.0 30.2 N 15.0 51.2 O 10.0 68.9 P 19.0 35.6 Q 19.0 37.8 R 9.0 41.3 S 10.5 69.0 T 11.0 61.8 U 12.0 47.6 V 15.0 60.8 W 15.0 54.4 X 15.0 19.5 Y 15.0 17.6 Z 12 100.0 AA 15 100.0 BB 19 100.0

The Surlyn® ionomers can be used individually, or can be blended. For instance, a 50/50 blend of ionomer E and ionomer M resulted in suitable materials for the cover of the invention. See Table 3. TABLE 3 A 50/50 Blend of Two Different Ionomers Type of Ionomer Wt % Acid Mol % Neutralization E 15.0 42.2 M 15.0 30.2 50/50 E and M 15.0 36.2

Example 5 Two Piece Golf Ball with Increasing Percent Neutralization Gradient

The inner core is made of ionomer having a neutralization of less than 70% and a single cover layer having a neutralization of greater than 80%.

In a different embodiment, the inner core is made of ionomer having a neutralization of less than 60% and a cover layer having a neutralization of greater than 90%

Example 6 Two Piece Golf Ball with Decreasing Percent Neutralization Gradient

The inner core is made of ionomer having a neutralization of greater than 80% and a single cover layer having a neutralization of less than 70%.

In a different embodiment, the inner core is made of ionomer having a neutralization of greater than 90% and a cover layer having a neutralization of less than 60%

Example 7 Three Piece Golf Ball with Increasing Percent Neutralization Gradient

The innermost core is made of neutralized ionomeric polymer material having a neutralization of less than 60%. The intermediate layer is made of ionomer having a neutralization of 60% to 89%. The cover is made of ionomer having a neutralization of greater than 90%.

Example 8 Three Piece Golf Ball with Decreasing Percent Neutralization Gradient

The innermost core is made of ionomer having a neutralization of greater than 90%. The intermediate layer is made of ionomer having a neutralization of 60% to 89%. The cover is made of neutralized ionomeric polymer material having a neutralization of less than 60%.

Example 9 Four Piece Golf Ball with Increasing Percent Neutralization Gradient

The innermost core is made of ionomer having a neutralization of less than 70% or made from a thermoset polybutadiene. The outer core is made of ionomer having a neutralization of 70% to 84%. The inner cover layer is made of ionomer having a neutralization of 85% to 99%. The cover is made of ionomer having a neutralization of 100%.

Example 10 Four Piece Golf Ball with Decreasing Percent Neutralization Gradient

The innermost core is made of ionomer having a neutralization of 100% or made from a thermoset polybutadiene. The outer core is made of Ionomer having a neutralization of 85% to 99%. The inner cover layer is made of ionomer having a neutralization of 70% to 84%. The cover is made of ionomer having a neutralization of less than 70%.

Example 11 Golf Ball Having Greater Than 40% Thermoplastic Contents and At Least Three Adjacent Ionomeric Layers

The core is made of thermosetting material with a diameter of 1.4 inches. The rest of the golf ball is made of thermoplastic materials such that the volume percent of thermoplastic materials is about 42.1%. The outer core is made of ionomeric material having a neutralization of about 35% or more. The intermediate layer is made of ionomeric material having a neutralization of about 40% or more. The inner cover is made of ionomeric material having a neutralization of about 50% or more. The cover is a 50/50 blend of ionomers E/M. See Table 3.

The percent neutralization gradient may also be decreasing from the center.

Example 12 Golf Ball Having Greater Than 40% Thermoplastic Contents and At Least Two Adjacent Ionomeric Layers

The core is made of thermosetting material with a diameter of 1.4 inches. The rest of the golf ball is made of thermoplastic materials such that the volume percent of thermoplastic materials is about 42.1%. The intermediate layer is made of ionomeric material having a neutralization of about 55%. The cover is made of ionomeric material having a neutralization of about 65%.

The percent neutralization gradient may also be decreasing from the center.

Example 13

Golf Ball Having Greater Than 40% Thermoplastic Contents and At Least Two Adjacent Ionomeric Layers That Are Not Highly Neutralized

Example 13 is the same as Example 12, except that the neutralized ionomers are not highly neutralized.

All patents, publications, test procedures, and other references cited herein, including priority documents, are fully incorporated by reference to the extent such disclosure is not inconsistent with this invention and for all jurisdictions in which such incorporation is permitted.

Other than in the operating examples, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials and others in the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear with the value, amount or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the-specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used.

While the illustrative embodiments of the invention have been described with particularity, it will be understood that various other modifications will be apparent to and can be readily made by those of ordinary skill in the art without departing from the spirit and scope of the invention. Accordingly, it is not intended that the scope of the claims appended hereto be limited to the examples and descriptions set forth herein, but rather that the claims be construed as encompassing all of the features of patentable novelty which reside in the present invention, including all features which would be treated as equivalents thereof by those of ordinary skill in the art to which the invention pertains. 

1. A multilayer golf ball comprising a core, an intermediate layer, and a cover, the intermediate layer and cover bring adjacent to each other, wherein at least one of the intermediate layer or cover comprises a first highly neutralized moisture resistant acid polymer composition having a moisture vapor transmission rate of 8 g-mil/100in2/day or less; the adjacent intermediate layer or cover comprises a second highly neutralized acid polymer; and the two adjacent layers, in tandem, form a percent neutralization gradient.
 2. The golf ball of claim 1, wherein the percent neutralization gradient progressively increases toward the outside of the golf ball.
 3. The golf ball of claim l, wherein the percent neutralization gradient progressively decreases toward the outside of the golf ball.
 4. The golf ball of claim 1, wherein the first highly neutralized moisture resistant acid polymer has a moisture vapor transmission rate of 5 g-mil/100 in²/day or less.
 5. The golf ball of claim 4, wherein the first highly neutralized moisture resistant acid polymer has a moisture vapor transmission rate of 3 g-mil/100 in²/day or less.
 6. The golf ball of claim 1, wherein at least one of the first and second highly neutralized acid polymers comprise acid groups that are at least 90% neutralized.
 7. The golf ball of claim 6, wherein at least one of the first and second highly neutralized acid polymers comprises acid groups that are 100% neutralized.
 8. The golf ball of claim 1, wherein the first highly neutralized moisture resistant acid polymer is neutralized with less hydrophilic cation sources selected from the group consisting of metal ions and compounds of potassium, cesium, calcium, barium, manganese, copper, zinc, and tin.
 9. The golf ball of claim 1, wherein the golf ball has a first volume and the layers formed from the first and second highly neutralized acid polymers combine to have a second volume that is at least 40 percent of the first volume.
 10. The golf ball of claim 9, wherein the second volume is at least 70 percent of the first volume.
 11. The golf ball of claim 10, wherein the second volume is at least 90 percent of the first volume.
 12. A multi-layer golf ball comprising a core and at least three adjacent layers comprising highly-neutralized acid polymers, the three adjacent layers comprising an innermost layer, an intermediate layer, and an outermost layer, wherein the golf ball has a first volume and a combination of the innermost, intermediate, and outermost adjacent layers form a percent neutralization gradient and have a second volume that is at least about 40% of the first volume.
 13. The golf ball of claim 12, wherein the percent neutralization gradient progressively increases toward the outside of the golf ball.
 14. The golf ball of claim 12, wherein the percent neutralization of the innermost layer is from about 20 to 70, the percent neutralization of the intermediate layer is from about 50 to 90, and the percent neutralization of the outermost layer is from about 70 to 100, and wherein the percent neutralization of the innermost layer is less than the percent neutralization of the intermediate layer, and the percent neutralization of the intermediate layer is less than the percent neutralization of the outermost layer.
 15. The golf ball of claim 12, wherein the percent neutralization gradient progressively decreases toward the outside of the golf ball.
 16. The golf ball of claim 12, wherein the percent neutralization of the innermost layer is from about 70 to 100, the percent neutralization of the intermediate layer is from about 50 to 90, and the percent neutralization of the outermost layer is from about 20 to 70, and wherein the percent neutralization of the innermost layer is greater than the percent neutralization of the intermediate layer, and the percent neutralization of the intermediate layer is greater than the percent neutralization of the outermost layer.
 17. The golf ball of claim 12, wherein the second volume is at least 70% of the first volume.
 18. The golf ball of claim 17, wherein the second volume is at least 90% of the first volume.
 19. A multi-layer golf ball comprising a core layer, an intermediate layer adjacent to the core layer, and an outermost layer adjacent to the intermediate layer, wherein the golf ball has a first volume and at least two of the adjacent layers comprise a neutralized acid polymer, said two adjacent layers combining to form a percent neutralization gradient.
 20. The golf ball of claim 19, wherein the combined adjacent layers have a second volume that is at least 40% of the first volume.
 21. The golf ball of claim 20, wherein the second volume is at least 70% of the first volume.
 22. The golf ball of claim 21, wherein the second volume is at least 90% of the first volume.
 23. The golf ball of claim 19, wherein the percent neutralization gradient progressively increases toward the outside of the golf ball.
 24. The golf ball of claim 19, wherein the percent neutralization gradient progressively decreases toward the outside of the golf ball.
 25. The golf ball of claim 19, wherein the neutralized acid polymer comprises acid groups that are neutralized from about 80 to 100%. 